UV-curable resin composition and display device

Abstract

This ultraviolet-curable resin composition comprises: component (A), which is a monofunctional aromatic (meth)acrylate having one aromatic ring; and component (B), which is a monofunctional aromatic (meth)acrylate having at least two aromatic rings, wherein the total amount of components (A) and (B) with respect to the total 100 parts by mass of a polymerizable compound in the ultraviolet-curable resin composition is at least 70 parts by mass.

Description

Technical Field

[0001] The present invention relates to an ultraviolet curable resin composition and a display device.

Background Art

[0002] Studies have been made to improve the properties of sealants for display elements and the like. Hereinafter, an organic EL display device will be described as an example.

[0003] Since organic EL elements consume little power, they are being used in displays, lighting devices, and the like. Since organic EL elements are liable to deteriorate by moisture and oxygen in the atmosphere, it has been studied to use them sealed with a sealing material.

[0004] Patent Document 1 (Japanese Patent Application Laid-Open No. 2020-506251) discloses a curable ink composition containing at least one aromatic (meth)acrylate, at least one polyfunctional (meth)acrylate having a group containing both a heteroaromatic group, a condensed aromatic group, a heteroalkylene group, or a heteroalkylene group and an aromatic group, and a photoinitiator, which is inkjet printable, has a viscosity of 30 centipoises or less at a temperature of room temperature to 35°C, does not contain a solvent, and has a refractive index of 1.55 or more and is optically transparent when printed and cured (Claim 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In recent years, as flat panels have become a common technology, OLED panels that can be held in a folded shape have been developed from the perspective of efficient use of space and design. Furthermore, there is a demand for devices with a high degree of freedom of movement, such as foldable panels and rollable panels. However, on the other hand, if the repulsive force when bending the encapsulating material in such a device is high, there was a concern that the force trying to return to its original shape would concentrate stress on the inorganic film or other material deposited on top of it, causing cracks to form. On the other hand, if the sealing material is designed to be flexible, there are concerns that the surface hardness will decrease, leading to process degradation such as surface tack and whitening. Therefore, the present invention provides a technique for obtaining a cured product that is highly flexible and has a desirable surface hardness. [Means for solving the problem]

[0007] According to the present invention, the following ultraviolet-curable resin composition and display device are provided. [1] The following components (A) and (B): (A) Monofunctional aromatic (meth)acrylate having one aromatic ring (B) Monofunctional aromatic (meth)acrylates having two or more aromatic rings A UV-curable resin composition containing, An ultraviolet-curable resin composition in which the total amount of components (A) and (B) relative to 100 parts by mass of the total amount of polymerizable compounds in the ultraviolet-curable resin composition is 70 parts by mass or more. [2] The ultraviolet curable resin composition according to [1], further comprising the following component (C). (C) Trifunctional (meth)acrylate [3] The UV-curable resin composition according to [1] or [2], wherein the viscosity measured by an E-type viscometer at 25°C and 20 rpm is 50 mPa·s or less. [4] The ultraviolet curable resin composition according to any one of [1] to [3], wherein the peak value of tanδ in the viscoelasticity measurement of the cured film of the ultraviolet curable resin composition is 1.4 or higher. [5] The ultraviolet curable resin composition according to any one of [1] to [4], wherein the refractive index of the cured film of the ultraviolet curable resin composition is 1.57 or higher. [6] The ultraviolet curable resin composition according to any one of [1] to [5], wherein the glass transition temperature Tg of the cured film of the ultraviolet curable resin composition is 60°C or less. [7] The ultraviolet curable resin composition according to any one of [1] to [6], wherein the total content of bifunctional or more (meth)acrylates in the ultraviolet curable resin composition is 30 parts by mass or less per 100 parts by mass of the total content of the polymerizable compound. [8] The ultraviolet curable resin composition according to any one of [1] to [7], wherein component (B) is a compound having a biphenyl skeleton. [9] The ultraviolet curable resin composition according to any one of [1] to [8], wherein component (B) is an ether-modified aromatic (meth)acrylate.

[10] The ultraviolet curable resin composition according to any one of [1] to [9], wherein the content of component (C): trifunctional or more (meth)acrylate in the ultraviolet curable resin composition is 10 parts by mass or less per 100 parts by mass of the total polymerizable compounds.

[11] A UV-curable resin composition according to any one of [1] to

[10] , further comprising a photopolymerization initiator.

[12] The UV-curable resin composition according to

[11] , wherein the photopolymerization initiator is diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO).

[13] An ultraviolet-curable resin composition according to any one of [1] to

[12] , used for coating by an inkjet method.

[14] An ultraviolet-curable resin composition according to any one of [1] to

[13] , for use as a display element.

[15] The ultraviolet-curable resin composition according to

[14] , wherein the display element is an organic electroluminescent element.

[16] A display device comprising a substrate, a light-emitting element disposed on the substrate, and a resin layer covering the light-emitting element, The display device, wherein the resin layer contains a cured product of the ultraviolet curable resin composition according to any one of [1] to

[14] .

[17] The display device according to

[16] , wherein the light emitting element includes an organic electroluminescence element. [Advantages of the Invention]

[0008] According to the present invention, it is possible to provide a technique for obtaining a cured product having excellent flexibility and a preferable surface hardness. [Brief Description of the Drawings]

[0009] [Figure 1] It is a cross-sectional view showing a configuration example of an organic EL display device in an embodiment. [Embodiments for Carrying Out the Invention]

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by common reference numerals, and the description thereof will be omitted as appropriate. Further, in the present embodiment, each component may be used alone or in combination of two or more. In addition, "~" representing a numerical range represents "more than or equal to" and "less than or equal to", and includes both the upper limit value and the lower limit value.

[0011] (Ultraviolet curable resin composition) In the present embodiment, the ultraviolet curable resin composition (hereinafter, also simply referred to as "resin composition" as appropriate) contains the following components (A) and (B), and the total content of the components (A) and (B) with respect to 100 parts by mass in total of the content of the polymerizable compounds in the resin composition is 70 parts by mass or more. (A) Monofunctional aromatic (meth) acrylate having one aromatic ring (B) Monofunctional aromatic (meth) acrylate having two or more aromatic rings

[0012] The inventor of the present invention has studied to make the cured product of the resin composition excellent in flexibility and have a preferable surface hardness. As a result, it has been found that by combining the components (A) and (B) and controlling the total amount of the components (A) and (B), a material with high bending followability can be obtained. Thereby, according to the present embodiment, the balance between the flexibility and the surface hardness of the cured product of the resin composition can be made excellent. In addition, according to the present embodiment, it is also possible to obtain, for example, a cured product excellent in flexibility and excellent in the effect of suppressing process deterioration.

[0013] Hereinafter, the configuration of the resin composition will be described more specifically. First, specific examples of the constituent components of the resin composition will be described.

[0014] (Polymerizable compound) The resin composition in the present embodiment contains a polymerizable compound, and contains the following components (A) and (B) as the polymerizable compound. Specifically, the polymerizable compound is a compound having a radically polymerizable functional group such as a (meth)acryloyl group. Here, in the present specification, the (meth)acryloyl group means at least one of an acryloyl group and a methacryloyl group. Also, (meth)acrylic means at least one of acrylic and methacrylic. Also, (meth)acrylate means at least one of acrylate and methacrylate. Also, EO is ethylene oxide.

[0015] (Component (A)) Component (A) is a monofunctional aromatic (meth)acrylate having one aromatic ring. Component (A) specifically includes benzyl acrylate (e.g., Viscoat #160, manufactured by Osaka Organic Chemical Industry Co., Ltd.); phenoxy group-containing (meth)acrylates such as phenoxyethyl (meth)acrylate (e.g., Viscoat #192); phenol EO-modified (meth)acrylates (e.g., Aronics® M-101A (approximately 2 moles of EO added), M-102 (approximately 4 moles of EO added), both manufactured by Toagosei Co., Ltd.); and alkylphenol EO-modified (meth)acrylates such as nonylphenol EO-modified acrylates (e.g., Aronics® M-111 (approximately 1 mole of EO added), M-113 (approximately 4 moles of EO added), both manufactured by Toagosei Co., Ltd.).

[0016] The content of component (A) in the resin composition is greater than 0 parts by mass, preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more, relative to 100 parts by mass of the total content of polymerizable compounds in the resin composition, from the viewpoint of viscosity adjustment for improved coatability and maintenance of surface hardness. Furthermore, from the viewpoint of improving flexibility, the content of component (A) in the resin composition is less than 100 parts by mass, preferably 80 parts by mass or less, more preferably 60 parts by mass or less, even more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less, based on the total content of polymerizable compounds in the resin composition.

[0017] (Component (B)) Component (B) is a monofunctional aromatic (meth)acrylate having two or more aromatic rings. Specific examples of component (B) include biphenyl skeleton-containing (meth)acrylates such as ethoxylated-o-phenylphenol acrylate (e.g., A-LEN-10, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) and phenoxyphenyl skeleton-containing (meth)acrylates (e.g., POB-A, manufactured by Kyoeisha Chemical Co., Ltd.). From the viewpoint of having high flexibility and maintaining surface hardness, component (B) is preferably a compound having a biphenyl skeleton. Furthermore, component (B) may be an ether-modified aromatic (meth)acrylate, such as ethoxylated-o-phenylphenol acrylate (e.g., A-LEN-10, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.).

[0018] The content of component (B) in the resin composition is greater than 0 parts by mass, preferably 20 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 50 parts by mass or more, and even more preferably 55 parts by mass or more, relative to 100 parts by mass of the total content of polymerizable compounds in the lipid composition, from the viewpoint of improving flexibility and refractive index. Furthermore, from the viewpoint of improving inkjet ejection performance, the content of component (B) in the resin composition is less than 100 parts by mass, preferably 90 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 70 parts by mass or less, relative to 100 parts by mass of the total content of polymerizable compounds in the resin composition.

[0019] The total content of components (A) and (B) in the resin composition is 70 parts by mass or more, preferably 75 parts by mass or more, more preferably 80 parts by mass or more, and even more preferably 90 parts by mass or more, based on 100 parts by mass of the total content of polymerizable compounds in the resin composition, from the viewpoint of achieving both flexibility and surface hardness. Furthermore, from the viewpoint of adjusting viscosity for inkjet ejection, the total content of components (A) and (B) in the resin composition is 100 parts by mass or less, or for example, 98 parts by mass or less, relative to 100 parts by mass of the total content of polymerizable compounds in the resin composition.

[0020] The resin composition may also contain polymerizable compounds other than components (A) and (B). Examples of polymerizable compounds other than components (A) and (B) include the following component (C).

[0021] (Component (C)) Component (C) is a (meth)acrylate with three or more functionalities. Specific examples of component (C) include trifunctional (meth)acrylic compounds such as trimethylolpropane triacrylate (e.g., A-TMPT, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.; light acrylate TMP-A, manufactured by Kyoeisha Chemical Co., Ltd.), ethoxylated trimethylolpropane triacrylate (e.g., A-TMPT-EO, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), ethoxylated glycerin triacrylate (e.g., A-GLY-6E, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), propoxylated glycerin triacrylate (e.g., A-GLY-3P, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), trimethylolpropane trimethacrylate (e.g., TMPT, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), and tris-(2-acryloxyethyl) isocyanurate (e.g., A-9300, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.); Tetrafunctional (meth)acrylic compounds such as pentaerythritol tetraacrylate (e.g., A-TMMT, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), ethoxylated pentaerythritol tetraacrylate (e.g., ATM-4E, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), and ditrimethylolpropane tetraacrylate (e.g., AD-TMP-L, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.); Pentafunctional (meth)acrylic compounds such as dipentaerythritol pentaacrylate; and Examples include hexafunctional (meth)acrylic compounds such as dipentaerythritol hexaacrylate (e.g., GM66G0H, manufactured by Kokusei Chemical Co., Ltd.). Furthermore, an example of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate is M-402 (manufactured by Toagosei Co., Ltd.).

[0022] The content of component (C) in the resin composition is, for example, 0 parts by mass or more, preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, even more preferably 4 parts by mass or more, and even more preferably 4.8 parts by mass or more, relative to 100 parts by mass of the total content of polymerizable compounds in the resin composition, from the viewpoint of reducing plasticity and reducing damage to organic EL elements in the plasma processing process. Furthermore, from the viewpoint of maintaining flexibility, the content of component (C) in the resin composition is 30 parts by mass or less, preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 5 parts by mass or less, based on 100 parts by mass of the total content of polymerizable compounds in the resin composition.

[0023] Furthermore, from the viewpoint of maintaining flexibility, the total content of bifunctional or more (meth)acrylates in the resin composition is 30 parts by mass or less, preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, based on 100 parts by mass of the total content of polymerizable compounds in the resin composition. Furthermore, from the viewpoint of reducing plasticity, the total content of bifunctional or more (meth)acrylates in the resin composition is, for example, 0 parts by mass or more, preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, based on 100 parts by mass of the total content of polymerizable compounds in the resin composition.

[0024] Here, among (meth)acrylates with two or more functions, the aforementioned compounds are specific examples of (meth)acrylates with three or more functions. Furthermore, specific examples of difunctional (meth)acrylates include di(meth)acrylates of diols and di(meth)acrylates of (poly)alkylene glycols, and more specifically, 1,6-hexanediol diacrylate (e.g., A-HD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), 1,9-nonanediol diacrylate (e.g., A-NOD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.; Light Acrylate 1,9ND-A, manufactured by Kyoeisha Chemical Co., Ltd.; Viscoat 260, manufactured by Osaka Organic Chemical Industry Co., Ltd.), 1 ,10-decanediol diacrylate (e.g., A-DOD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), neopentyl glycol diacrylate (e.g., A-NPG, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.; light acrylate NP-A, manufactured by Kyoeisha Chemical Co., Ltd.), ethylene glycol diacrylate (e.g., SR206NS, manufactured by Arkema), polyethylene glycol diacrylate (e.g., A-400, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), polypropylene glycol diacrylate (e.g., APG-400, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) (Manufactured by Nakamura Chemical Industry Co., Ltd.), tricyclodecanedimethanol diacrylate (dimethylol-tricyclodecanediaacrylate) (e.g., A-DCP, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.; Light acrylate DCP-A, manufactured by Kyoeisha Chemical Co., Ltd.), 1,3-butanediol dimethacrylate (e.g., BG, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), 1,4-butanediol dimethacrylate (e.g., BD, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), 1,6-hexanediol dimethacrylate (e.g., HD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) Examples include 1,9-nonanediol dimethacrylate (e.g., NOD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), 1,10-decanediol dimethacrylate (e.g., DOD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), 1,12-dodecanediol diacrylate (e.g., SR-262, manufactured by Sartomer Co., Ltd.), neopentyl glycol dimethacrylate (e.g., NPG, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), and tricyclodecanedimethanol dimethacrylate (e.g., DCP, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.). From the viewpoint of obtaining more favorable flexibility and surface hardness of the cured product, the content of the difunctional (meth)acrylate is preferably 10% by mass or less, more preferably 7% by mass or less, even more preferably less than 5% by mass, even more preferably less than 2% by mass, and even more preferably 1% by mass or less, relative to the total composition of the resin composition. Furthermore, from the viewpoint of making the flexibility and surface hardness of the cured product more desirable, the content of the bifunctional (meth)acrylate is preferably 35 parts by mass or less, more preferably 25 parts by mass or less, even more preferably 15 parts by mass or less, even more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, and even more preferably 1 part by mass or less, based on 100 parts by mass of the total content of polymerizable compounds in the resin composition.

[0025] From the viewpoint of improving the strength of the cured product, the total content of polymerizable compounds in the resin composition is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 85% by mass or more, and even more preferably 90% by mass or more, relative to the total composition of the resin composition. Furthermore, the total content of polymerizable compounds in the resin composition is, for example, 99.9% by mass or less, preferably 99.5% by mass or less, and more preferably 99% by mass or less, relative to the total composition of the resin composition.

[0026] In this embodiment, the resin composition may contain components other than polymerizable compounds. Other examples of components include polymerization initiators, tackifiers, photosensitizers, leveling agents, and coupling agents such as silane coupling agents.

[0027] (Polymerization initiator) In this embodiment, the resin composition specifically further contains a polymerization initiator, and preferably further contains a photopolymerization initiator.

[0028] Specifically, photopolymerization initiators are photoradical generators. Specific examples of photoradical generators include one or more selected from the group consisting of acyloxine phosphide compounds, oxime ester compounds, alkylphenone compounds, and benzophenone derivatives.

[0029] Specific examples of acyloxine phosphide compounds include 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO: e.g., Omnirad TPO, manufactured by IGM Resins) and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (e.g., Omnirad 819, manufactured by IGM Resins). Furthermore, specific examples of oxime ester compounds include Irgacure OXE01, Irgacure OXE02, Irgacure OXE03, and Irgacure OXE04. From the viewpoint of improving curability, the photopolymerization initiator is preferably TPO.

[0030] From the viewpoint of improving curability, the content of polymerization initiator in the resin composition is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, per 100 parts by mass of the total resin composition. Furthermore, from the viewpoint of suppressing discoloration of the resin composition, the content of the polymerization initiator in the resin composition is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, even more preferably 6 parts by mass or less, and even more preferably 4 parts by mass or less, based on 100 parts by mass of the total resin composition.

[0031] (Adhesion agent) By including a tackifier in the resin composition, the internal stress of the resin composition can be relaxed without significantly changing the refractive index of the cured resin composition, and more specifically, the internal stress during curing of the resin composition can be reduced. Specifically, examples of tackifiers include at least one resin selected from the group consisting of petroleum resins such as aliphatic hydrocarbon resins, alicyclic hydrocarbon resins, and aromatic hydrocarbon resins; terpene resins; phenolic resins; terpene-phenolic resins; and rosin resins.

[0032] Specific examples of petroleum resins include: C5 monomers or oligomers obtained from pentene, pentadiene, isoprene, etc.; C9 monomers or oligomers obtained from indene, methylindene, vinyltoluene, styrene, α-methylstyrene, β-methylstyrene, etc.; copolymers of C5 monomers and C9 monomers (C5-C9 copolymer resins); alicyclic monomers or polymers obtained from cyclopentadiene, dicyclopentadiene, etc.; aromatic monomers or polymers such as isopropenyltoluene; hydrides of the above monomers or polymers thereof; and modified petroleum resins obtained by modifying the above monomers or polymers thereof with maleic anhydride, maleic acid, fumaric acid, (meth)acrylic acid, phenol, etc. From the viewpoint of excellent compatibility with polymerizable compounds, the petroleum resin is preferably a styrene oligomer.

[0033] Examples of terpene resins include aromatically modified terpene resins obtained by copolymerizing terpenes such as α-pinene resin, β-pinene resin, α-pinene monomer, and β-pinene monomer with aromatic monomers such as styrene.

[0034] Phenolic resins specifically include condensates of phenols and formaldehyde. Examples of phenols include phenol, m-cresol, 3,5-xylenol, p-alkylphenol, and resorcinol. Examples of phenolic resins include resols obtained by the addition reaction of these phenols and formaldehyde with an alkaline catalyst, and novolacs obtained by the condensation reaction with an acid catalyst. Phenolic resins also include rosinphenol resins obtained by thermal polymerization after adding phenol to rosin with an acid catalyst.

[0035] Furthermore, copolymers of terpenes and phenols can be used as terpene phenol resins.

[0036] Specific examples of rosin resins include gum rosin, wood rosin, or tall oil rosin; stabilized rosin or polymerized rosin obtained by disproportionation or hydrogenation treatment using these rosins; modified rosin obtained by modifying these rosins with maleic anhydride, maleic acid, fumaric acid, (meth)acrylic acid, phenol, etc.; and esterified products thereof. The alcohol used to obtain the esterified product is preferably a polyhydric alcohol. Examples of polyhydric alcohols include one or more selected from the group consisting of dihydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, and neopentyl glycol; trihydric alcohols such as glycerin, trimethylolethane, and trimethylolpropane; tetrahydric alcohols such as pentaerythritol and diglycerin; and hexahydric alcohols such as dipentaerythritol.

[0037] From the viewpoint of improving the viscosity and inkjet coating properties of the resin composition, the content of the tackifier in the resin composition is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 1.5% by mass or more, and also preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less, relative to the total composition of the resin composition.

[0038] (Leveling agent) By further including a leveling agent in the resin composition, the flatness of the film formed by the resin composition can be improved. Specific examples of leveling agents include silicone-based leveling agents such as polyester-modified polydimethylsiloxane (e.g., BYK-310, manufactured by BIC Chemie Japan) and polyether-modified siloxane (e.g., BYK-345, manufactured by BIC Chemie Japan); Acrylic leveling agents such as acrylic copolymers (e.g., BYK-350, manufactured by Bic Chemie Japan; KL700, manufactured by Kyoeisha Chemical Co., Ltd.; Polyflow No. 90, manufactured by Kyoeisha Chemical Co., Ltd.); Examples of fluorine-based leveling agents include fluorine-modified polymers (e.g., BYK-340, manufactured by BIC Chemie Japan) and perfluoroalkyl-containing oligomers (e.g., Surflon S-611, manufactured by AGC Seimi Chemical).

[0039] From the viewpoint of improving flatness when applying a resin composition to inkjet printing, the leveling agent is preferably one or more selected from the group consisting of acrylic copolymers, polyester-modified polydimethylsiloxanes, and fluorine-modified polymers. From a similar perspective, it is also preferable that the leveling agent is an acrylic-based leveling agent.

[0040] From the viewpoint of improving the flatness of the film formed by the resin composition, the content of the leveling agent in the resin composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, and even more preferably 0.5% by mass or more, relative to the total composition of the resin composition. Furthermore, from the viewpoint of stabilizing the surface hardness of the cured product, the content of the leveling agent in the resin composition is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 2% by mass or less, relative to the total composition of the resin composition.

[0041] (solvent) In this embodiment, the resin composition preferably does not contain a solvent, or if the resin composition contains a solvent, the solvent content is greater than 0% by mass, 0.05% by mass or less, and more preferably 0.03% by mass or less. A specific example of a resin composition that does not contain a solvent is one in which the solvent is not intentionally blended during the preparation of the resin composition.

[0042] From the viewpoint of suitability for ejection from an inkjet nozzle, the resin composition in this embodiment is preferably liquid. The viscosity of the resin composition, measured using an E-type viscometer at 25°C and 20 rpm, is preferably 1 mPa·s or higher, more preferably 4 mPa·s or higher, even more preferably 7 mPa·s or higher, even more preferably 10 mPa·s or higher, even more preferably 13 mPa·s or higher, and even more preferably 16 mPa·s or higher, from the viewpoint of improving the effect of suppressing dripping during inkjet ejection. Furthermore, from the viewpoint of enabling more stable inkjet ejection, the viscosity of the resin composition is preferably 50 mPa·s or less, more preferably 35 mPa·s or less, and even more preferably 30 mPa·s or less.

[0043] In the viscoelasticity measurement of the cured film of the resin composition, the peak value of tanδ is preferably 1.40 or higher, more preferably 1.60 or higher, even more preferably 1.75 or higher, even more preferably 1.80 or higher, and even more preferably 1.9 or higher, from the viewpoint of improving flexibility while maintaining hardness. Furthermore, the peak value of tanδ mentioned above may be, for example, 10.0 or less.

[0044] From the viewpoint of improving flexibility, the glass transition temperature Tg of the cured film of the resin composition is preferably 60°C or lower, more preferably 55°C or lower, even more preferably 50°C or lower, even more preferably 45°C or lower, and even more preferably 40°C or lower. Furthermore, from the viewpoint of suppressing surface tack, the above Tg is preferably -10°C or higher, more preferably 0°C or higher, even more preferably 10°C or higher, and even more preferably 20°C or higher.

[0045] Here, the peak value of tanδ and Tg in the viscoelasticity measurement of the cured film of the resin composition are measured by the following method. (Method of manufacturing cured film) The resin composition is sealed inside two glass plates with a 100 μm thick Teflon® sheet sandwiched in between, and illuminated with a 395 nm wavelength UV-LED at an illuminance of 1000 mW / cm². 2 , cumulative light intensity 4000 mJ / cm 2 A cured material with a thickness of 100 μm obtained by curing is cut to a size of 5 mm wide x 45 mm long, and the cured material is used as a sample if the thickness at a total of four points, every 10 mm along the length, is all in the range of 90 to 110 μm. (Methods for measuring tanδ and Tg) Measurements will be performed in accordance with JIS K7244-4:1999. Specifically, the dynamic viscoelasticity of the obtained cured film will be measured using a dynamic viscoelasticity analyzer "DMS6100" (manufactured by Seiko Instruments Corporation) at a frequency of 1 Hz, a heating rate of 5 °C / min, and a temperature range of 25 °C to 150 °C. The storage modulus E' and loss modulus E'' will be measured, and the loss tangent, i.e., tanδ = loss modulus E'' / storage modulus E', will be calculated, with its maximum value being defined as the peak value of tanδ. The temperature at which tanδ is maximum will be defined as the glass transition temperature Tg.

[0046] From the viewpoint of providing excellent flexibility through intermolecular interactions, the refractive index of the cured film of the resin composition is preferably 1.57 or higher, more preferably 1.575 or higher, even more preferably 1.58 or higher, and even more preferably 1.59 or higher. Furthermore, the refractive index may be, for example, 1.70 or less. Here, the cured film of the resin composition, which is the sample for measuring the refractive index, is prepared in the same manner as the sample for measuring tanδ. Furthermore, the refractive index of the cured film is specifically the refractive index (nd) of the cured material at room temperature (25°C) in the d-line (wavelength 587.6 nm), and can be measured using an Abbe refractometer based on JIS standard K0062-1992.

[0047] Next, we will explain the method for producing the resin composition. The method for producing the resin composition is not limited and may include, for example, mixing components (A) and (B) and other components as appropriate. As a method for mixing each component, for example, a method of uniformly kneading under conditions such as room temperature or heating, atmospheric pressure, reduced pressure, pressurized pressure or inert gas flow, using various known kneaders such as planetary agitators, homodispersers, universal mixers, Banbury mixers, kneaders, two-roll, three-roll, and extruders, either alone or in combination.

[0048] In this embodiment, the obtained resin composition can also be used to form a sealing material. For example, the resin composition may be applied to a substrate and dried. Known methods such as inkjet printing, screen printing, and dispenser coating can be used for application. Drying can be performed by heating to a temperature at which the polymerizable compound does not polymerize. There are no restrictions on the shape of the resulting sealing material; for example, it can be in the form of a film.

[0049] Furthermore, the resin composition in this embodiment is suitably used for coating by inkjet printing.

[0050] The resin composition in this embodiment is preferably for display elements, and more preferably for organic electroluminescent (EL) elements. Furthermore, the resin composition in this embodiment is preferably suitable for use as a encapsulating material for display elements such as organic EL elements. Furthermore, by using the cured resin composition obtained in this embodiment as a encapsulating material for display elements such as organic EL display elements, a display device with excellent manufacturing stability and design flexibility can be obtained. The following are examples of OLED display configurations.

[0051] (Organic EL display device) In this embodiment, the organic EL display device has a layer made of a cured resin composition. Figure 1 is a cross-sectional view showing an example of the configuration of an organic EL display device in this embodiment. The display device 100 shown in Figure 1 is an organic EL display device and includes a substrate (base layer 50), an organic EL element (light-emitting element 10) disposed on the base layer 50, and a sealing layer 22 (which may be an overcoat layer 22 or a barrier layer 22) that covers the light-emitting element 10. For example, the sealing layer 22 is made of a cured product of the resin composition in this embodiment. Furthermore, in Figure 1, the display device 100 has a barrier layer 21 (which may be a touch panel layer 21 or a surface protection layer 21), a sealing layer 22 (which may be an overcoat layer 22 or a barrier layer 22), a planarization layer 23 (which may be a sealing layer 23), and a barrier layer 24 as layers located on the observation side of the light-emitting element 10. The planarization layer 23 is provided on the substrate layer 50 so as to cover the light-emitting element 10, and the barrier layer 24 is provided on the surface of the planarization layer 23. The sealing layer 22 is provided on the substrate layer 50 so as to cover the planarization layer 23 and the barrier layer 24. In addition, the barrier layer 21 is provided on the sealing layer 22.

[0052] The specific configuration of each layer is not limited, and an appropriate configuration can be adopted for each based on generally known information. Furthermore, such a display device 100 can be manufactured based on generally known information. [Examples]

[0053] The present invention will be described below with reference to examples, comparative examples, and reference examples, but the present invention is not limited thereto.

[0054] First, the materials used in the following example are shown. (polymerizable compound) (A) Polymerizable compound 1 (monofunctional aromatic acrylate): benzyl acrylate (CAS No. 2495-35-4), Viscoat #160, manufactured by Osaka Organic Chemical Industry Co., Ltd. (B) Polymerizable compound 2 (monofunctional aromatic acrylate): Ethoxylated-o-phenylphenol acrylate (CAS No. 72009-86-0), A-LEN-10, manufactured by Shin Nakamura Chemical Industry Co., Ltd. (A) Polymerizable compound 3 (monofunctional aromatic acrylate): Nonylphenol EO-modified acrylate (number of EO addition moles ≈ 1), Arronix® M-111, manufactured by Toagosei Co., Ltd. Polymerizable compound 4 (difunctional methacrylate): 1,12-dodecanediol dimethacrylate (CAS No. 72829-09-5), SR-262, manufactured by Sartomer. Polymerizable compound 5 (difunctional methacrylate): 1,9-nonanediol dimethacrylate (CAS No. 65833-30-9), NOD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd. Polymerizable compound 6 (monofunctional acrylate): Isostearyl acrylate (CAS No. 93841-48-6), S1800A, manufactured by Shin-Nakamura Chemical Industry Co., Ltd. (C) Polymerizable compound 7 (pentaerythritol hexa-functional acrylate): A mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (a mixture of CAS No. 60506-81-2 and 29570-58-9), M-402, manufactured by Toagosei Co., Ltd. (C) Polymerizable compound 8 (trifunctional acrylate): Tris-(2-acryloxyethyl) isocyanurate (CAS No. 40220-08-4), A-9300, manufactured by Shin Nakamura Chemical Industry Co., Ltd. (C) Polymerizable compound 9 (trifunctional diacrylate): Trimethylolpropane triacrylate (CAS No. 15625-89-5), A-TMPT, manufactured by Shin Nakamura Chemical Industry Co., Ltd.

[0055] (Tackifire) Tackifier 1: Aromatic hydrocarbon resin 1: Styrene oligomer A; Homopolymer of isopropenyltoluene (IPT) (weight average molecular weight: 1200, number average molecular weight: 800) (Leveling agent) Leveling agent 1: Acrylic copolymer, Polyflow No. 90, manufactured by Kyoeisha Chemical Co., Ltd. (Polymerization initiator) Photopolymerization initiator 1: 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, TPO, manufactured by IGM Resins.

[0056] (Examples 1-12, Comparative Examples 1-2, Reference Example 1) Each component was blended to obtain a liquid, solvent-free, curable resin composition as shown in Table 1. The physical properties of the resin compositions or their cured products obtained in each example were measured by the following method. The measurement results are shown in Table 1.

[0057] (viscosity) The viscosity of the resin compositions obtained in each example was measured using an E-type viscometer (LV DV-II+ Pro, BROOKFIELD) at 25°C and 20 rpm.

[0058] (tanδ, Tg) The peak value of tanδ and Tg of the cured film of the resin composition obtained in each example were measured by the following method. The resin composition is sealed inside two glass plates with a 100 μm thick Teflon® sheet sandwiched in between, and illuminated with a 395 nm wavelength UV-LED at an illuminance of 1000 mW / cm². 2 , cumulative light intensity 4000 mJ / cm 2 The cured material obtained by curing was cut to a size of 5 mm wide x 45 mm long, and the cured material (self-supporting film) was used as a sample, with a thickness of 90 to 110 μm at a total of four points 10 mm apart along the length. The obtained cured film was subjected to dynamic viscoelasticity measurements using dynamic mechanical analysis (DMS, DMS6100, Seiko Instruments Corporation) based on JIS K7244-4:1999. The measurements were performed at a frequency of 1 Hz, a heating rate of 5°C / min, a temperature range of 23°C to 150°C, a strain amplitude of 5 μm, a minimum tension / compression force of 50 mN, a tension / compression force gain of 1.2, an initial force amplitude of 50 mN, a sampling time of 3 s, a chuck distance of 20 mm, and a rate of 98.0665 mN / min in SS control mode. The storage modulus E' and loss modulus E'' were measured, and the loss tangent, i.e., tanδ = loss modulus E'' / storage modulus E', was determined, with its maximum value taken as the peak value of tanδ. Furthermore, the temperature at which the above tanδ is maximized was defined as the glass transition temperature Tg (°C).

[0059] (Refractive index) The refractive index of the cured film of the resin composition obtained in each example was measured by the following method. The refractive index (nd) of the cured film at room temperature (25°C) in the d-line (wavelength 587.6 nm) was obtained by measuring the cured film with an Abbe refractometer, in accordance with JIS standard K0062-1992.

[0060] (CVD) The following CVD evaluation method was used to assess organic EL element damage during the plasma processing process. Coating films for obtaining cured products for CVD evaluation were prepared by the following method. Specifically, the resin compositions obtained in each example were introduced into an inkjet cartridge DMC-11610 (manufactured by Fujifilm Dimatix). The inkjet cartridge was then set in an inkjet device DMP-2831 (manufactured by Fujifilm Dimatix), and after adjusting the ejection state, the coating was applied to alkali-free glass in a 5cm x 5cm size so that the cured thickness would be 10μm. The resulting coating film was irradiated with a UV-LED with a wavelength of 395 nm at an irradiance of 1000 mW / cm². 2 , cumulative light intensity 4000 mJ / cm 2 The material was cured at an oxygen concentration of 1000 ppm or less. Subsequently, aluminum was deposited to a thickness of 100 nm onto the inkjet-coated surface, and the dielectric constant was measured at 100 kHz using the automatic balancing bridge method with an LCR meter HP4284A (manufactured by Agilent Technologies). A 1 μm SiN film with a refractive index of 1.7 was deposited on the obtained samples using the parallel plate method at 110°C. The condition after film deposition was evaluated according to the following criteria, and those with grades A and B were considered acceptable. C: Peeling present. B: Partial peeling present. A: No peeling.

[0061] (Inkjet ejection stability) The resin compositions obtained in each example were placed in an inkjet cartridge DMC-11610 (manufactured by Fujifilm Dimatix, with 16 nozzles), the ejection state was adjusted, and then the cartridges were stored at 25°C and 50% RH for 90 days before ejection. If the number of non-ejecting nozzles was less than 30%, the result was classified as A; if it was 30% or more, the result was classified as B.

[0062] (Film bending and followability test) As indicators of the surface hardness and flexibility of the cured film, self-supporting films of the resin compositions obtained in each example were prepared using the following method, and a film bending follow-through test was performed. Except for setting the width of the cured material to 30 mm, the cured film (self-supporting film) was prepared in accordance with the previously described method for measuring tanδ and Tg. At 25°C, the obtained self-supporting film was wrapped around a 1cm diameter smooth stainless steel rod. When unwound, it was graded D if it was broken, C if it was partially broken, B if it was tightly adhered by tack, and A if it was neither broken nor tightly adhered. Films graded A through C were considered acceptable.

[0063] [Table 1]

[0064] In Table 1, the unit for each component amount is parts by mass. As shown in Table 1, in each example, a cured product with flexibility and desirable surface hardness was obtained, and it also exhibited excellent suppression of damage to organic EL elements during CVD deposition and inkjet ejection stability.

[0065] This application claims priority based on Japanese Patent Application No. 2022-017906, filed on 8 February 2022, and incorporates all of its disclosures herein. [Explanation of symbols]

[0066] 10 light-emitting elements 21 Barrier layer, touch panel layer, or surface protective layer 22. Sealing layer, overcoat layer, or barrier layer 23. Planarization layer or sealing layer 24 Barrier layer 50 Base material layer 100 display device

Claims

1. The following components (A) and (B): (A) Monofunctional aromatic (meth)acrylate having one aromatic ring (B) Monofunctional aromatic (meth)acrylates having two or more aromatic rings A UV-curable resin composition containing, The total amount of components (A) and (B) relative to 100 parts by mass of the total amount of polymerizable compounds in the ultraviolet-curable resin composition is 70 parts by mass or more. It is for use as a sealing material for display elements. The ultraviolet-curable resin composition wherein the total content of bifunctional or more (meth)acrylates in the ultraviolet-curable resin composition is 1 part by mass or more and 30 parts by mass or less per 100 parts by mass of the total content of the polymerizable compound.

2. The ultraviolet-curable resin composition according to claim 1, wherein the display element is an organic electroluminescent element.

3. The ultraviolet-curable resin composition according to claim 1 or 2, further comprising the following component (C). (C) (meth)acrylates with three or more functional properties

4. The ultraviolet-curable resin composition according to claim 1 or 2, wherein the viscosity measured by an E-type viscometer at 25°C and 20 rpm is 50 mPa·s or less.

5. The ultraviolet-curable resin composition according to claim 1 or 2, wherein the peak value of tanδ in the viscoelasticity measurement of the cured film of the ultraviolet-curable resin composition is 1.4 or higher.

6. The ultraviolet-curable resin composition according to claim 1 or 2, wherein the refractive index of the cured film of the ultraviolet-curable resin composition is 1.57 or higher.

7. The ultraviolet-curable resin composition according to claim 1 or 2, wherein the glass transition temperature Tg of the cured film of the ultraviolet-curable resin composition is 60°C or less.

8. The ultraviolet-curable resin composition according to claim 1 or 2, wherein the component (B) is a compound having a biphenyl skeleton.

9. The ultraviolet-curable resin composition according to claim 1 or 2, wherein the component (B) is an ether-modified aromatic (meth)acrylate.

10. The ultraviolet-curable resin composition according to claim 1 or 2, wherein the content of component (C): trifunctional or higher (meth)acrylate in the ultraviolet-curable resin composition is 10 parts by mass or less per 100 parts by mass of the total polymerizable compounds.

11. The ultraviolet-curable resin composition according to claim 1 or 2, further comprising a photopolymerization initiator.

12. The ultraviolet-curable resin composition according to claim 11, wherein the photopolymerization initiator is diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (TPO).

13. An ultraviolet-curable resin composition according to claim 1 or 2, used for coating by an inkjet method.

14. A display device comprising a substrate, a light-emitting element disposed on the substrate, and a resin layer covering the light-emitting element, A display device comprising a resin layer containing a cured product of the ultraviolet-curable resin composition described in claim 1 or 2.

15. The display device according to claim 14, wherein the light-emitting element includes an organic electroluminescent element.

Images